One of the most robust phenomena in animal learning is the rat's ability to associate flavored substances with toxin-induced internal aversive states. Previous investigations of taste-aversion learning have stressed the noncognitive, primitive aspects of this conditioning, arguing that the learning invariably occurs when a novel flavor is experienced in conjunction with toxicosis. In contrast to this emphasis, recent findings from our laboratories suggest that informational variables also have an important role in taste-aversion conditioning. The proposed experiments will extend and analyze our preliminary findings. Three approaches to the investigation of informational influences on learning about edibles will be pursued. One will focus on the deleterious effects on taste-aversion learning of presenting the aversion-inducing agent (lithium chloride in most of the experiments) shortly (30-90 min.) before a taste-toxicosis conditioning trial. The second set of experiments will determine the effects of a taste experience on the short- and long-term processing of information concerning either that same flavor or a different taste. The third investigation will explore the mechanisms and boundary conditions of the interference with taste-aversion learning which occurs when a previously-conditioned taste is present during the conditioning of a novel flavor. Each investigation will be designed to evaluate competing theoretical explanations of the results. Theories, such as Wagner's recent priming and rehearsal model, which are relevant to all three of the proposed lines of research will be given disparate approaches to the study of informational influences on learning about edibles.